ATLANTA -- Metro Atlantans concerned about the cost of a new Falcons stadium should take note: in the case of each of the four most recently built NFL stadiums, the price tag only went up as construction went along.

11Alive News researched the numbers on the new stadiums in Arizona, Indianapolis, Dallas, and New Jersey.

In Arizona, the Cardinals and the state's Sports & Tourism Authority began planning a new stadium at the beginning of last decade. Initial estimates had the project costing $331 million, but by its conclusion it cost roughly $455 million.

In Indianapolis, preliminary figures saw Lucas Oil Stadium costing $500 million. Four years later, the stadium opened in 2008 with a final price tag of $720 million.

In Dallas, Jerry Jones' Cowboys Stadium was estimated as a $650 million project. It wound up costing nearly double that amount: $1.2 billion.

And in New Jersey, the new home of the Jets and Giants was planned to cost $800 million. By its end, MetLife Stadium became the most expensive stadium in the world, costing $1.6 billion.

MetLife Stadium is privately funded, the only one of the four not to cost taxpayer money. In Arizona and Dallas, politicians ensured that the teams and their owners would pay for any additional costs.